An image forming apparatus typically refers to an apparatus configured to form an image on a printing medium in accordance with an input signal. Examples of image forming apparatuses include printers, photocopiers, facsimiles, and multifunction devices that integrate or combine some of the functions of such apparatuses.
An electro-photographic image forming apparatus, which is a type of the image forming apparatus, can produce an image on a printing medium by using the following general processes. A surface of a photoconductive medium is charged to a predetermined electrical potential. A light having information corresponding to image data is made incident upon the charged photoconductive medium to form an electrostatic latent image on the surface of the photoconductive medium. Developer is applied to the electrostatic latent image to form a visible image. The visible image on the photoconductive medium can be transferred to a printing medium directly or indirectly through an intermediate transfer unit. The transferred visible image can be fixed on the printing medium by using a fixing process.
Typically, the printing medium, which is initially flat, can become curled during the fixing process because of the high heat and pressure used during the process. The curled printing medium may be passed between two discharging rollers having different solidities in an attempt to correct the curling.